Microfluidic applications often require fluid-tight connections to be made between two initially separate conduits. Conventional techniques for connecting conduits include the use of ferrules and other types of machined fittings, and certain adhesives such as UV-curable adhesives. Many problems attend conventional fluid connections, particularly in microfluidic applications. Machined fittings such as ferrules tend to be bulky and thus are often not suitable for applications requiring installation in tight spaces. Machined fittings and adhesives typically do not provide an acceptably long enough service life in microfluidic applications involving very high fluid pressures, such as HPLC (high-performance liquid chromatography). Machined fittings and adhesives typically cannot provide robust connections between two conduits made from dissimilar materials or two conduits of different sizes.
Additionally, machined fittings and adhesives may not provide fluidic connections of acceptable sealing integrity in low-flow (micro-scale or nano-scale flow) applications, which require conduits having inside diameters on the order of tens of microns. Conduits on this scale are particularly desirable in low-flow analytical separation systems such as low-flow HPLC systems, and in low-flow ionization devices utilized in atmospheric pressure ionization (API) such as small-scale electrospray probes (which may be coupled to HPLC systems). Low-flow regimes require small cross-sectional flow areas to ensure that sharp, highly discernable (low dispersion) signal peaks will be produced from analytes carried in the fluid flow. Fluid connections employed in such applications should be configured to ensure high peak resolution.
Therefore, there is an ongoing need for improved fluid connections between conduits, particularly in microfluidic applications, and for devices and assemblies employing such connections.